Performance of Weathered Steel Guardrail in NC.

摘要

Weathered steel beam guardrail is a popular alternative to galvanized steel guardrail as an aesthetic solution that blends in with the surrounding natural environment. A research study from New Hampshire found that weathered steel guardrail deteriorated quicker than galvanized steel guardrail leaving erratic motorists without a safe roadside barrier. Weather conditions and de-icing chemicals play an obvious role in the deterioration of guardrail. These weather conditions vary across geographical regions, raising the question whether the New Hampshire findings are applicable to North Carolina locations. Nonetheless, the New Hampshire study is being recommended by the Federal Highway Administration for adoption across the country. Some North Carolina weathered steel guardrail installations from the 1980s and 1990s have provided a significant length of service; leading many to believe the findings from New Hampshire might not apply to other states with less severe weather conditions. Eliminating a potential guardrail treatment based on a non-comparable study location is not good engineering practice. Since weathered steel is more aesthetically pleasing and a preferable alternative in many natural environments, this study measures the rate of deterioration under North Carolina specific conditions. The study findings will be valuable to guide further guardrail installation and replacement decisions in North Carolina. The team did not find any trends of deteriorating thickness as a function of guardrail age (oldest installation is almost 30 years old), elevation (highest average installation elevation is 4,200 feet), and AADT (highest traffic is 27,000 vehicles per day). The structural analysis therefore suggests no concerns of using weathered steel beam guardrail in the state of North Carolina. Collision analysis found that weathered steel beam guardrail collisions did not result in more severe collisions than galvanized steel guardrail, and that the severity of collisions decreased over the study period.